Wildly unpredictable performance issues!

I purchased an early 2008 dual quad-core 2.8 Ghz Mac Pro 3,1 for the almost-too-good-to-be-true price of $400 from eBay.

When it arrived, it was lacking a video card, the feet were badly bent and I found that the RAM was mostly non-functional.

I have made my peace with the leaning tower, installed 16 gigs of RAM brand new and because money is tight, I installed an NVIDIA GT 520 video card with 1024 MB of memory. I have no boot-up screen but once the Mac gets to the sign-in screen, all is good.

For the first 5 months after the Mac Pro was a champ! But in the last month, I've noticed that one of the front USB ports suddenly quit working. Internal hard drives will be randomly ejected without warning. I had a terrible scare when one of them ejected unexpectedly and wouldn't show up again even after moving the sled from one slot to another and restarting the Mac numerous times, but it lately just popped back up of its own volition.

I've ran SMART tests on all the hard drives and they're fine according to different tests. I've gotten a copy of the Apple's Hardware Test but my Mac Pro flat-out refuses to boot from the disc I burned so I'm stumped as to how I can narrow down the gremlin that is troubling my machine. I have a sinking suspicion that it might be the logic board although I've noticed some peculiar video artifacts when I visit websites that demand Web GL so that would tend to make me suspicious of the non-EFI video card too.

I have a buddy that has an identical Mac Pro but he has rebuffed my requests to borrow his video card so I could have a stock set up temporarily to attempt testing it again.

At this point, I'm at a loss as to my next step: should I just chuck this machine into the recycling bin and hope to score another Mac Pro with similar horsepower or maybe settle for an iMac from around 2009 or 2010?

I use my Mac to edit a lot of video (both SD and HD) and also a far bit of photogrammetry. I'm on a very tight budget these days and the most I could really afford to spend would be in the neighborhood of about $900.

The prices for a replacement logic board and/or video card are eye-wateringly high for a machine of this vintage.

Does anyone have any advice or ideas? I'm a Mac enthusiast at best so I don't know as much as many others here.

4 Soluções

These older Mac Pro's have gained still more value after the new Mac Pro was announced by Apple as many people like the internal storage options and have managed to upgrade the processors to what they need.

Can you give us the last three digits of your S/N (or Model Identifier) so we can ID which model you have and the OS-X version you are working with.

I hadn't thought of the EFI/SMC firmware needing an update so I followed your link. Everything checked out as being updated. I downloaded the installer just-in-case and ran it anyway. It informed me I was current.

My external 3 terabyte by Western Digital was a favorite target of the ejection-gremlin. I've confirmed it's S.M.A.R.T. status. Everything seems to be intact on it so far. It is less than a year old. I've switched the USB plug to a different port as an experiment; it seems to be ejected less frequently.

The hard drive in Bay Two (where my iPhoto Library lives) is the same. I'm leaning towards replacing it anyway as it is stamped 2007. I'm guessing it came stock in the Mac.

I just tried once again to run the Apple Hardware Test program by booting from the CD I burned. The Mac just sits there with a dark screen (maybe the non-EFI video card?) until it gets to the sign-in screen.

Your external drive should be self powered so that would not be an issue for it (power). Yes, the video card could be whats stopping you running AHT. It does take some time to run so get a cup of coffee to see if you're just being to impatient ;-}

LOL! Well I tried running the AHT several times now, but it never tells me anything as the Mac just simply goes to the sign-in screen after a moment. It doesn't seem to take anymore than 20-30 seconds from the time I start till the sign-in screen pops up, just like normal.

Maybe I should try finding someone with a video card I could "borrow" for an hour or two?

Wow-ed by the low price and seemingly amazing processors on these things, my friend and I both had this exact machine as our primary workstations up until about a year ago, and we both gave them up because no matter how much RAM we threw at them, they suffered from very odd and intermittent performance slowdowns that were almost impossible to determine the source of. I had an 8800GT video card, so it was definitely not due to a lack of GPU. I don't like to be so vague in my description of a problem, but I definitely believe there is some kind of performance bottleneck with this model...possibly due to the 800MHZ bus, or a lack of optimization for current OS versions. It also only supports SATA2, and has problems with lots of newer and larger drives (don't try to use a 3TB drive as your boot drive).

So with my experience in mind, I'd hate to see you drop a ton of money on this machine, only to potentially hit the same wall that I did. I currently have a dual-core 2.9GHZ i7 MacBook Pro, and performance is infinitely improved (something you wouldn't necessarily expect from a laptop, or considering the difference in processor cores).

Are we talking about the same model here?? Each of two 45-nm Xeon E5462 (Harpertown/Penryn) processors has four independent processor "cores" with 12 MB of level 2 cache per processor (each pair of cores shares 6 MB). It also features a 128-bit SSE4 SIMD vector engine, and 1.6 GHz "64-bit dual independent frontside buses." (From EveryMac)

If you have matched modules (interleaved) the functional speed is 1600MHz (2x800MHz). Granted its not the same as a single memory module running at the 1600MHz DDR3 speed. But it's not as bad at a single module running at 800MHz either. We don't have any Mac Pro's any more so I can't tell you what we had or how they where configured. I also don't remember us having any issues running heavy graphics and CAD software on them either. We moved to iMacs and Mac mini's for the offices. We just got in our first Mac Pro '13 today. Can't wait to check it out in the coming weeks ;-}

I'm having the exact issue as stated above, narrowed it down to a power issue. I have a bid in on a power supply to see if that will fix it but I'm worried it's actually just a problem with the power delivery on the main board. Basically as soon as there is load on all 8 cores $@$* goes haywire. After a few seconds the core clocks drop randomly to 2.4ghz incurring a freeze at every transition, and there is near constant micro-stutter when games are attempted to be played.

Sucks because when it was running well, it was insane I was playing games nearly maxed out on an 8 year old machine... But it's not running well anymore and I think I need to give up and get a dedicated gaming PC.